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Discussion Starter · #1 ·
So I finally figured out what was making my 84 Shelby charger HO run really rich at idle. The timing belt was really stretched and the cam sprocket had massive play on the cam shaft!
So what I did is found my M.P. mild comp turbo cam I had on my 86 t1 Shelby charger and bolted it to a 88 cam sprocket off a 2.5 T1. I held up the stock HO cam sprocket to the 88 sprocket and saw the 88 was a little more retarded than the stock HO. I have also read the turbo cam is more retarded than what comes on the stock HO setup.
So my question is how many degree's is one tooth of the cam sprocket and how many degree's am I retarding the cam with this setup. The car is running great but it still idles a little rich. I'm wondering if it would be safe to advance the cam sprocket by one tooth or is it not retarded enough to do that.
 

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One tooth = 9 cam degrees = 18 crank degrees.
Most likely the cam is either where it needs to be or 4 cam degrees retarded.
Would need to know the cam sprocket numbers and exactly which cams.
 

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I am a little confused, sounds like you need to purchase an adjustable cam sprocket to fine tune your cam timing for your setup.

84-88 use a square tooth cam sprocket.
89-up use a round tooth cam sprocket

84-87 T1/T2 Cam - .430 Lift 240/240 Duration
88 TBI and Turbo - .430 Lift 236/232 Duration 4 degrees reatrded from the 89-up Turbo Cam.
89-up .430 Lift 228/228 Duration

84 -87 are Slider Cams and 88- up are roller cams.
You cannot use the roller cam without installing the roller rockers.

Donavans Dodge Garage lists all the different Cam's and Cam Sprockets for our cars.
Click on turbo database, Link 04 Camshafts, Sprockets, etc.
 

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Discussion Starter · #4 ·
I am using the MP slider cam. Its for the 86 782 turbo 1 head. The cam sprocket is the round tooth off a 89 turbo mini van.
The round tooth sprocket has 40 teeth so 9% per thooth. The 89 cam sprocket looks to be a half of one tooth retared compared to the 84 HO cam sprocket, that would be 4%. the 84 cam sprocket I am told is already 4% retarded compared to stock. So that would be a total of 8% retarted compared to stock just in the cam sprocket. The timing belt I'm using is a universal. It can be installed on either cam sprocket. I noticed the teeth looked funny on the new belt so I had him look it up and its the same P# for the 89 mini van. From what I understand the turbo cam shaft is also retarded a few degrees compared to a stocker 2.2 carbed 84. right now the car is running 2.5 sec. faster 0-60 with this cam and sprocket but I'm hitting max HP at 6200 rpm. At the rev limit. I want to bring the power band down and get better gas milage.

I'm just going to advance it one tooth on the cam and let you how it goes.
 

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I lost you at the universal belt...
Both cam and crank sprockets are round tooth correct?
The MP cam is most likely 240/248 dur. int/exh, .460" lift both lobes, 24' overlap, 110' centerline.

The stock 84 carb cam would have had a 108-112' centerline (not familiar with the early carb cars, just going off the specs) and about the same duration. The HO cam sprocket if I recall from reading was 4' retarded over a stock N/A sprocket.

The later round tooth cam I've been told has the same installed angle but for the wider lobed 114' centerline of the later roller cam, resulting in 4' of retard when applied to the older square sprocket for the 110' centerline cams.

In the end honestly I cannot confirm the sprocket differences or the old stock cam LSA, so I won't BS you.

Personally I would try advancing a tooth since it's a N/A engine, and give the ol'seat of the pants dyno a check. If that helps then invest in a cam sprocket or set of cam keys and really get it on the sweet spot.
 

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Discussion Starter · #6 ·
Yea thats the next step in this little project before I turbo it. Cam keys. I'm just looking to get good gas milage for now to save up money for the head I want and to finish building the 2.2 tubo block. If I wanted good power now, I would leave it the way it is. Its screaming compared to the stock HO. But.... I just want good gas and good pep. But cam keys would be good. But I don't realy have all the specs down anyway to use them right.
 

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Technically, if the HO sprocket is 4 degrees retarded, and the 88 cam is 4 degrees retarded in relation to the HO sprocket, then advancing the cam one tooth would put you at 1 degree advance past centerline.

I would just swap the cam gears from the HO cam onto your MP cam.
 
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